AC Clutch Don't Engage With 12V Jumped To Pigtail

[DaraSue]

I'm having the same issue. #10 fuse is fine. Last fall I accidentally yanked the wire that goes to the compressor loose while trying to take the intake manifold off. It came apart at this junction and I can feel it click into place (I think) when I try to put it back together, but the center of the compressor still doesn't turn.

56269

It's this compressor (r-134), looks kind of the aftermarket one DMCH sells but I don't think it actually is.

56270

What are the odds that something else just happened to go wrong after I messed with that wire? The A/C was working fine last fall. I haven't used it all that much (probably less than 8 hours total in almost 2 years, mostly for less than 20 minutes at a time if I'm in stop and go traffic, once for a few hours on the way back from Vegas). The compressor was replaced by the seller and the lines were replaced at DMCMW after I bought it (it still had the old R12 fittings). They put 12oz of 134 back in it b/c it had been leaking with the old fittings. It can't have all gotten used up since then, right?

that black wire goes into the compressor between the pulley and the body of the compressor, is there anything user-serviceable in there? I'm worried that I yanked something loose on the compressor side of it.

[Bitsyncmaster]

You can test if you have leaked refrigerant by jumping the low pressure switch connections. Other than that test you would need a multimeter to trace if a connection got broken.

[Ron]

I'm having the same issue. #10 fuse is fine. Last fall I accidentally yanked the wire that goes to the compressor loose while trying to take the intake manifold off. It came apart at this junction and I can feel it click into place (I think) when I try to put it back together, but the center of the compressor still doesn't turn.

56269

It's this compressor (r-134), looks kind of the aftermarket one DMCH sells but I don't think it actually is.

56270

What are the odds that something else just happened to go wrong after I messed with that wire? The A/C was working fine last fall. I haven't used it all that much (probably less than 8 hours total in almost 2 years, mostly for less than 20 minutes at a time if I'm in stop and go traffic, once for a few hours on the way back from Vegas). The compressor was replaced by the seller and the lines were replaced at DMCMW after I bought it (it still had the old R12 fittings). They put 12oz of 134 back in it b/c it had been leaking with the old fittings. It can't have all gotten used up since then, right?

that black wire goes into the compressor between the pulley and the body of the compressor, is there anything user-serviceable in there? I'm worried that I yanked something loose on the compressor side of it.
No, it shouldn't use any, ever. Leaks should be the only loss.

You can check the compressor end by disconnecting its pig tail and jumping it momentarily to the 12V (+) jump post. If it engages, follow the suggestions above to continue. ...probably better to start your own thread to avoid confusion tho.

[DaraSue]

Thanks, guys. I wasn't sure if it would be a greater sin to threadjack or to start another thread about a similar issue.

Just one more question - if I'm getting current on the wire that comes out of the harness to the compressor, does that mean it's not the low pressure switch cutting it off?

[DMC-Ron]

Thanks, guys. I wasn't sure if it would be a greater sin to threadjack or to start another thread about a similar issue.

Just one more question - if I'm getting current on the wire that comes out of the harness to the compressor, does that mean it's not the low pressure switch cutting it off?

Dara,
With the key on (engine can be off) and the mode selector turned to AC (NORM), you should hear your cooling fans come on and you should have +12 on the wire to the compressor clutch.

If you do, then check to see if the compressor clutch is engaging. You should hear a "thunk" sound. If not, check that wire connector again that was in your picture. Perhaps it is not completely connected.

If you do not get cooling fans and there is no power on the compressor wire, jumper the low pressure switch to see if the fans come on and compressor clutch engages. If so, it would indicate low refrigerant.

Ron

56272

[DaraSue]

Dara,
With the key on (engine can be off) and the mode selector turned to AC (NORM), you should hear your cooling fans come on and you should have +12 on the wire to the compressor clutch.

If you do, then check to see if the compressor clutch is engaging. You should hear a "thunk" sound. If not, check that wire connector again that was in your picture. Perhaps it is not completely connected.

If you do not get cooling fans and there is no power on the compressor wire, jumper the low pressure switch to see if the fans come on and compressor clutch engages. If so, it would indicate low refrigerant.

Ron

56272

The fans do come on, I don't have my meter with me but the test light comes on if I stick the probe into the switch side of the connector. The clutch just doesn't engage.

I'll try jumping the compressor end of the wire when I get home and see what happens. It feels like it snaps into place when I connect the ends together but maybe something's broken inside the sheathing.

[Ron]

Thanks, guys. I wasn't sure if it would be a greater sin to threadjack or to start another thread about a similar issue.

Just one more question - if I'm getting current on the wire that comes out of the harness to the compressor, does that mean it's not the low pressure switch cutting it off?
Yes...If you apply 12V to the compressor, regardless of where it comes from (jumper, pink harness wire, etc), the clutch should engage.
If it does not, it's probably the plug-in connection at the compressor, a bad clutch coil, or a wide clutch plate gap.
A non stock compressor coil may have a 2nd wire that must be grounded.

[DaraSue]

I tried running a store-bought jumper wire (with clips on each end) from the jumper post to the compressor plug and nothing happened, then it finally occurred to me to try sticking the test light where the wire goes into the body of the compressor and it still lit up. So I guess the problem is somewhere further down the line. I'll try and figure out what brand/model it is and how it's supposed to be wired and if I still can't spot anything obvious I guess it's time to take it to the shop.

Thanks everyone, hopefully some of my flailing with this is useful to Barry too...

[David T]

If you are getting 12 volts at the clutch and it still won't engage, measure the gap. I had one car with too big a gap and it would only engage when cold. Once it warmed up it would not engage again.

[Ron]

I tried running a store-bought jumper wire (with clips on each end) from the jumper post to the compressor plug and nothing happened, then it finally occurred to me to try sticking the test light where the wire goes into the body of the compressor and it still lit up. So I guess the problem is somewhere further down the line. I'll try and figure out what brand/model it is and how it's supposed to be wired and if I still can't spot anything obvious I guess it's time to take it to the shop. Unclear what you meant by "still".
Anyway, are you saying that, using a jumper wire, you jumped from the battery's jump post to the compressor's pigtail wire plug (right where the pink harness wire plugs in to it) and nothing happened (not even a faint spark), AND, you then disconnected the jumper wire and connected one end of a test light to the battery's jump post and the other end to the compressor's pigtail wire, not where the pink harness wire plugs into it but closer to the compressor (by piercing the insulation with the light's probe maybe)? If so, the first test says power did not get to the compressor coil, and the second test says it did. This sounds like the pig tail wire is broke under the insulation (probably right behind the plug).
Try connecting the jumper wire to the battery's jumper post and the same place you did with the test light (ie "where the wire goes into the compressor body" instead of the compressor's plug). Be careful, if it has a short and the jumper wire does not have a fuse, it will get HOT fast! If the clutch then engages, splice in a new plug. If not, but it sparks, the coil is weak or the gap is too wide...tap the clutch lightly and see if it engages. Otherwise, you must have done something wrong...

Hang in there....

[Bitsyncmaster]

Often if a meter or test light works and the load does not it points to a marginal connection because the load draws more current than the test loads.

But as Ron suggested a jumper from the battery jump terminal to the wire at the compressor clutch would show if the connection from the bulkhead to compressor were bad.

[DaraSue]

Yeah, I clipped one end of the jumper wire to the battery jump-start post and the other end to the pigtail plug (this one) 56275 and nothing happened. The motor was off at the time, was it supposed to be on? I had unplugged it from where it connected to the harness and connected the jumper clip to the metal part at the end of the black wire.

When I used the test light I was putting the probe at the other end of that wire, between the pulley and the body of the compressor, where the arrow is pointing here except further in: 56276 The probe was skinny enough to fit into that space and touch where there was a gap at the end of the sheathing but the clip on the jumper wire won't fit down in there so I'd have to strip the sheathing off farther up to try jumping it again between the plug and the compressor, I guess?

I also tried running a ground jumper wire between one of the bolts on the compressor and the ground loop on the engine block, and that didn't help, either.

The gap between the clutch and the pully might be another thing, though. I noticed upon closer inspection that it fits really tight on top but has more space on the bottom, that's not right, is it? Not sure how well it shows up in this pic but it looked like around 1mm on the bottom. 56277 56278

I asked the guy who sold me the car where it was from, he thought DPI but it doesn't look quite like the ones on their website. It has the number "B508SC02N" stamped on it but Google only returns a couple of Russian wholesale sites when I search for that. Probably not a good sign...

[dn010]

If you applied +12VDC from the jumper post or even the battery to rule out a bad jumper post connection and the clutch did not engage, then you've got issues with the clutch itself and not the wiring. The compressor looks quite new, perhaps the wire going in is broken? You'd need to pull the pulley/clutch off the compressor which is a PITA installed on the car but can be done if you have the tools/puller.

Before you get into all that, though, I'd hook up the +12V to the compressor connector and jump post, connect the test probe to ground somewhere and then probe the wire lower towards the pulley and see if the probe lights up. Be careful though, there is a lot of ground that the jumper can short out on being connected to the compressor connector. Wrap it up in a cloth or put a piece of cardboard etc between the jumped connector and compressor. The engine does NOT need to be running, nor does ignition need to be in for this, if you jump it from the jump terminal on side of the car by the bulkhead connectors. With any luck, maybe it is just a bad crimp on the connector which would be the easiest fix.

[David T]

For more info on the gap refer to N:10:08-:09 in your Workshop Manual. To verify if the coil for the clutch is any good apply 12 volts and see what the amps are or try to measure the resistance of the coil without power. if it doesn't draw any amps or you get infinite resistance the coil is bad or not connected at both ends.

[Ron]

Yeah, I clipped one end of the jumper wire to the battery jump-start post and the other end to the pigtail plug (this one) 56275 and nothing happened. The motor was off at the time, was it supposed to be on?
No...it doesn't matter.


When I used the test light I was putting the probe at the other end of that wire, between the pulley and the body of the compressor, where the arrow is pointing here except further in: 56276 The probe was skinny enough to fit into that space and touch where there was a gap at the end of the sheathing but the clip on the jumper wire won't fit down in there so I'd have to strip the sheathing off farther up to try jumping it again between the plug and the compressor, I guess?
Yes.
You might try piercing the insulation with something sharp an inch behind the plug and jumping 12V to it first (your probe, a large needle?).
If that didn't work, a stiff wire with the insulation stripped off of the very end might allow you to carefully reach in where you had the probe end...


I also tried running a ground jumper wire between one of the bolts on the compressor and the ground loop on the engine block, and that didn't help, either. The engine is grounding the compressor body...


The gap between the clutch and the pully might be another thing, though. I noticed upon closer inspection that it fits really tight on top but has more space on the bottom, that's not right, is it? Not sure how well it shows up in this pic but it looked like around 1mm on the bottom. 56277 56278
The gap wouldn't cause the two tests to differ -- I'd work on that first...

[DaraSue]

I tried sticking a t-pin a couple places along the compressor wire and jumping to that (I had to use a length of 12-gauge wire for the one where it went into the compressor because the jumper wire was too short) and still, nothing. It doesn't spark or even seem to get hot. What am I doing wrong? Should I pull one of my other cars up and try to jump straight from the battery? The test light shows current when jumpers are connected or when I connect it to the jumper post.

Also what does this ground wire do? It comes out of the harness and forks off from the same place as the a/c wire. I remember disconnecting it while working on the intake and it looks a little frayed at the connector.56290 (It's normally attached, I just unplugged it to try and tighten the bolt.)

[dn010]

That's the oil pressure sensor.

Anyway, if you attach the connector to +12VDC and then probe the wire with a tester connected to ground further down the line near the clutch, that will tell you if you're even getting power in the wire. If you do see power, then you know you have an issue inside. If you just try to apply 12V to the wire down the line, you still can't confirm that the wire is actually getting power or your're piercing the insulation unless you hook the test probe to the connector at the end and see it light up when you apply power down the wire.

[Ratrace427]

its just a bad clutch coil. its just a electro magnet that grounds through the mounting bolts for the compressor and gets its power through that single wire. you have given it everything needed to energize. the coil can be changed with a special puller. I have done this without taking the compressor out but you need the tools. depending on the compressor vendor these coils will go out often. darn junk parts.

you might get crafty and hold the plate and take the center nut loose. then use prying devices to pull the plate off. then a snap ring holds the coil on. usually this won't work without bending the clutch plate.

check the resistance between the power wire and the compressor case. most likely its open. I would have to check troubleshooting but it shouldn't be open. Sarah @ DMC will know the answer.

Buying a new compressor from dmc is fast and easy.

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[dn010]

... or you can diagnose before blowing $250. It’s really not that bad taking it apart IF you have some tools to do so as I already stated. I even have two compressor worth or parts if you need a working coil.


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[Ron]

I tried sticking a t-pin a couple places along the compressor wire and jumping to that (I had to use a length of 12-gauge wire for the one where it went into the compressor because the jumper wire was too short) and still, nothing. It doesn't spark or even seem to get hot. What am I doing wrong? Should I pull one of my other cars up and try to jump straight from the battery?
Sounds like you did everything right. If you are 100% sure you had a good 12V on the metal part inside the wire (near the red arrow in the pic), the clutch coil needs to come off to find the problem.

Also what does this ground wire do? Not really a ground wire, fwiw...It is grounded by the Oil Warning Lamp Sender, which grounds the bulb. (The pressure sender is on the opposite side of the block.)

[Ron]

That's the oil pressure sensor.

Anyway, if you attach the connector to +12VDC and then probe the wire with a tester connected to ground further down the line near the clutch, that will tell you if you're even getting power in the wire. If you do see power, then you know you have an issue inside. If you just try to apply 12V to the wire down the line, you still can't confirm that the wire is actually getting power or your're piercing the insulation unless you hook the test probe to the connector at the end and see it light up when you apply power down the wire.I don't know...Seems there is little difference in the reliability of piercing with a t-pin v/s a probe tip. And if he did see power, it would only confirm that the amount required to light a bulb can get from the connector to the wire...not enough.
Anyway, it sounds like he got power as close to the coil as possible w/o removing it to me??
I don't see him missing as many times as he has tried it, so I'm betting the coil or its connection to the pigtail is bad (at least ;-).

[DaraSue]

Thanks, everybody. I found some Chinese writing on the compressor wire so maybe it really was just a cheap one that coincidentally had the coil go bad. (Josh @ DPI verified that it wasn't one of his.) Not sure how confident I feel in my ability to get the clutch & pulley off without making an even bigger mess of it but I guess if it already doesn't work, it's worth a shot. Before I do anything I can't undo, a couple of questions -

1. I wouldn't have to empty the refrigerant out if I just took the clutch/pulley/coil out, right?

2. If I get them off and can't get them back on, it won't cause any problems to drive without the belt & pulley for as long as it takes to get to the shop, will it? Or longer than that?

Ideally I'd like to get it working before our club road trip to Bryce Canyon next month. I'd probably survive but IDK if I'll end up with a passenger...

[dn010]

Thanks, everybody. I found some Chinese writing on the compressor wire so maybe it really was just a cheap one that coincidentally had the coil go bad. (Josh @ DPI verified that it wasn't one of his.) Not sure how confident I feel in my ability to get the clutch & pulley off without making an even bigger mess of it but I guess if it already doesn't work, it's worth a shot. Before I do anything I can't undo, a couple of questions -

1. I wouldn't have to empty the refrigerant out if I just took the clutch/pulley/coil out, right?

2. If I get them off and can't get them back on, it won't cause any problems to drive without the belt & pulley for as long as it takes to get to the shop, will it? Or longer than that?

Ideally I'd like to get it working before our club road trip to Bryce Canyon next month. I'd probably survive but IDK if I'll end up with a passenger...

No, pulling the pulley off will not require emptying the system. You can drive without the AC belt for as long as it takes.




I don't know...Seems there is little difference in the reliability of piercing with a t-pin v/s a probe tip. And if he did see power, it would only confirm that the amount required to light a bulb can get from the connector to the wire...not enough.
Anyway, it sounds like he got power as close to the coil as possible w/o removing it to me??
I don't see him missing as many times as he has tried it, so I'm betting the coil or its connection to the pigtail is bad (at least ;-).


Don't you mean she?

The only reason I suggest connecting the +12V to the connector and then probing the wire lower is so you know that you've actually pierced through the insulation and have a connection. It doesn't really matter how you do it as long as you can confirm power is getting to the wire, that's all.

[Ron]

Don't you mean she?
One can never know these days, but yeah.:)

[Too many AC threads going...SORRY DaraSue!]


The only reason I suggest connecting the +12V to the connector and then probing the wire lower is so you...
I guess you meant she as well....:deviltail:

Seriously- I agree that it doesn't really matter how you do it as long as you can confirm power is getting to the wire. But it has to be "good" power -- Although a test light can confirm voltage is present, it can't confirm that the amount of amperage required by the coil is able to get through. So, if a connection between the connector and the wire existed, but it was too poor, the test would lead her to believe the connection (power) is OK when it actually can't handle the load required by the coil. A test light can only confirm there is no power, but then the next step would be to jump 12V straight to the wire anyway...which she did -- I'd say pull that puppy!

I guess it's beside the point here, but an Ohm meter would have been the way to go in the first place, of course...

======

DaraSue,
If you've decided to pull the coil but are uncomfortable with the piercing and all, you might try this first:
Turn the key to off.
Turn the widest gap in the clutch plate up to 12 o'clock.
Cut the wire behind the connector and strip it back enough to get a good connection for the jumper wire.
Connect the jumper wire to the jump post.
Make sure the jumper wire has a good 12V+ on the other end...
Connect it to the stripped wire.
Tap the plate toward the compressor at the wide gap with a tool handle or such to see if the plate snaps and stays closed.
If it does, you would need to see if there is 2 to 5 Ohms from ground to the stripped wire.
If there is, straighten and adjust the gap then try 12V to the stripped wire again...

[Bitsyncmaster]

It looks like the AC compressor hoses are not stock so if the owner decides to get a new compressor make sure you get one to match what you have for hose connections.

[DaraSue]

Well, I have no idea how or why, but it magically started working today. It occurred to me that I might have heard it click into place last time I tried turning the switches on with the key on but the engine off, so I started it up, and it was blowing ice cold (or as close to it as R134 gets). :yesss:

The only thing I did since the last time we talked was turn it around so the gap was on the top, and push on the clutch plate a little. Either that did something or I actually had pulled the coil end of the wire out when I accidentally yanked the connector apart last Nov. and poking and prodding it with the tester pushed it back into place. Weather permitting I'll drive it to work tomorrow and see what happens. :confused:

(No offense taken at being misgendered. This place is kind of a sausagefest so there was about a 90% chance... :wink: )

[Ron]

Cool!
Now try to get the plate gap even. (See N:10:09, Step 7) It doesn't say to, but try to close the wide side first...

(http://dmctalk.org/showthread.php?16458-AC-Clutch-Don-t-Engage-With-12V-Jumped-To-Pigtail&p=234337#post234337)

[Ratrace427]

Cool!
Now try to get the plate gap even. (See N:10:09, Step 7) It doesn't say to, but try to close the wide side first...

(http://dmctalk.org/showthread.php?16458-AC-Clutch-Don-t-Engage-With-12V-Jumped-To-Pigtail&p=234337#post234337)that's awesome! nothing better than when it fixes itself, but bad coils like to do that. If it stops working again that re-confirms the coil. I had one work one day and then stop the next. that same coil would work till it cycled then wouldn't come back. electronics and heat don't play well with each other.

you said you gave it a test power and ground source and it didn't work. either you made a simple mistake while doing this process or the clutch coil isn't happy.

let's hope you made a mistake =P

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[Ron]

+1!

Since it showed continuity to the pigtail wire (post 8), I wouldn't be surprised if the coil was getting power during the jumper tests but the uneven-wide gap prevented the plate from being pulled up and any obscure spark went unnoticed.
(Sometimes a good whack in the right place works wonders...;-)

Time will tell...

[DaraSue]

Well, so much for its miraculous recovery. On the way to work it blew cold for the first few miles, then crapped out. When I got there I tried tapping on it but nothing happened. Probably a flaky coil?

[Ron]

Well, so much for its miraculous recovery. On the way to work it blew cold for the first few miles, then crapped out. When I got there I tried tapping on it but nothing happened. Probably a flaky coil?
Sounds like it. Pull it off and see if the connection from the pigtail to the winding needs to be re-crimped/soldered.
Measure the resistance through the coil itself if you can...

[dn010]

If you can pull the coil, I’ll send you a working one, for the usual price of...free.


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[dn010]

A bit dirty but ready to go. 56302


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[Ron]

If you can pull the coil, I’ll send you a working one, for the usual price of...free.

8) ...gotta love this community!

[Ratrace427]

is that the correct coil for her replacement compressor? oh wait..never mind.

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[DaraSue]

Arrgh, I spent $25 on the clutch holder tool from Autozone but I still can't get the damn thing loose. It uses a 19mm nut and I can't seem to get enough leverage. I don't want to use the breaker bar or lean on the fascia too much in case I slip and break something that'll cost more than a couple hundred bucks to fix. Guess it's time to go back to the shop.

I checked the air gap with a spark plug gapper and it was .035-.038ish at the widest part, pretty much stuck against the pulley at the narrowest. Would that be enough to be causing these issues?

[Ratrace427]

Arrgh, I spent $25 on the clutch holder tool from Autozone but I still can't get the damn thing loose. It uses a 19mm nut and I can't seem to get enough leverage. I don't want to use the breaker bar or lean on the fascia too much in case I slip and break something that'll cost more than a couple hundred bucks to fix. Guess it's time to go back to the shop.

I checked the air gap with a spark plug gapper and it was .035-.038ish at the widest part, pretty much stuck against the pulley at the narrowest. Would that be enough to be causing these issues?meh.. sounds like it has some miles on it but that electro magnet is strong. that will note cause it from pulling up to the pulley.

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[Ron]

I agree. It is closer overall than normal....

[David T]

I checked the air gap with a spark plug gapper and it was .035-.038ish at the widest part, pretty much stuck against the pulley at the narrowest. Would that be enough to be causing these issues?


Yes. The gap should be closer to the lower spec, .016. Because it is difficult to get the gap consistent all around, it will vary but .038 is more than double what you want. Take it apart and reset the gap.

[DMC5180]

Typically, there is one shim washer installed in the OE unit that can be removed to bring it back too the bottom end of the spec. It is a one time fix for an otherwise wearing assembly. Once the gap wears above the max spec with no shim, it’s time for a new clutch assembly or whole new compressor assembly at that point in time.


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[DaraSue]

Gave up and took it to the shop today, refrigerant was slightly low (1.7 instead of 2 lbs) but he didn't think that would be enough to cause the clutch not to engage. He tried jumping it and whacking it with a rubber mallet too, to no avail. Checking the resistance just between the wire and the front of the clutch without taking it apart he thought it had a short in it, and that it would be less labor and a better chance of a long-lasting fix to just replace the whole compressor rather than trying to replace just the clutch/coil. He didn't think it was extremely likely that I'd caused it by pulling on the wire since it's clamped down pretty good by the coil but he couldn't 100% rule it out.

Talking to Mike @ Midwest he said that sometimes when people convert R12 to R134 they use the wrong kind of oil and it burns out the clutch faster. I wonder if that's what happened here b/c the last time it consistently worked I ran it for several hours in one go, whereas I only ever remember running it for <20 mins at a time before.

The adventure continues...